Multiple choice

A student's average score on 5 tests is 78. If the student takes a 6th test, and their average score for all 6 tests becomes 80, what score did the student get on the 6th test?

  1. 60

  2. 70

  3. 90

  4. 120

  5. 110
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C Correct answer
Explanation

Sum of 5 scores = 5 * 78 = 390. Sum of 6 scores = 6 * 80 = 480. The 6th test score = 480 - 390 = 90.

AI explanation

First, find the total score of the 5 tests by multiplying the average by the number of tests: 78 times 5 equals 390. Next, find the total score for all 6 tests: 80 times 6 equals 480. The score needed on the 6th test is the difference between the new total and the old total, so 480 minus 390 equals 90.

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